The present invention relates to an upshift control system for an automatic transmission.
There have been conventionally proposed upshift control systems for an automatic transmission. Japanese Patent Application First Publication No. 10-184882 (corresponding to U.S. Pat. No. 6,041,275) discloses an upshift control system for an automatic transmission which performs learning control of shift (changeover) timing for friction elements in the automatic transmission in order to provide a good shift feeling upon an upshift operation. In this conventional system, when engine racing is detected in a range in which an engagement pressure in an engagement-side (apply-side) friction element is larger than an engagement pressure in a disengagement-side (release-side) friction element, it is determined that the engine racing is caused due to lack of an engagement capacity of the engagement-side friction element, and therefore, the engagement pressure in the engagement-side friction element is allowed to increase. Further, when engine racing is detected in a range in which the engagement pressure in the disengagement-side friction element is larger than the engagement pressure in the engagement-side friction element, it is determined that the engine racing is caused due to lack of an engagement capacity of the disengagement-side friction element, and therefore, the engagement pressure in the disengagement-side friction element is allowed to increase.
Japanese Patent Application First Publication No. 7-12209 discloses a shift control system for an automatic transmission which aims to suppress engine racing or shock due to torque drop during a torque phase of upshift. The shift control system is adapted to optimally control timing of shift (changeover) by using a one-way clutch for the disengagement-side friction element and a hydraulic pressure switch (sensor) for the engagement-side friction element.